[PATCH] dma-buf: keep the signaling time of merged fences v2

[Alex Deucher]

On Fri, Jun 23, 2023 at 5:09 AM Christian König
<ckoenig.leichtzumerken at gmail.com> wrote:
>
> Some Android CTS is testing for that.
>
> v2: use the current time if the fence is still in the signaling path and
> the timestamp not yet available.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>

Acked-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  drivers/dma-buf/dma-fence-unwrap.c | 20 +++++++++++++++++---
>  drivers/dma-buf/dma-fence.c        |  5 +++--
>  drivers/gpu/drm/drm_syncobj.c      |  2 +-
>  include/linux/dma-fence.h          |  2 +-
>  4 files changed, 22 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
> index 7002bca792ff..46c2d3a474cd 100644
> --- a/drivers/dma-buf/dma-fence-unwrap.c
> +++ b/drivers/dma-buf/dma-fence-unwrap.c
> @@ -66,18 +66,32 @@ struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,
>  {
>         struct dma_fence_array *result;
>         struct dma_fence *tmp, **array;
> +       ktime_t timestamp;
>         unsigned int i;
>         size_t count;
>
>         count = 0;
> +       timestamp = ns_to_ktime(0);
>         for (i = 0; i < num_fences; ++i) {
> -               dma_fence_unwrap_for_each(tmp, &iter[i], fences[i])
> -                       if (!dma_fence_is_signaled(tmp))
> +               dma_fence_unwrap_for_each(tmp, &iter[i], fences[i]) {
> +                       if (!dma_fence_is_signaled(tmp)) {
>                                 ++count;
> +                       } else if (test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT,
> +                                           &tmp->flags)) {
> +                               if (ktime_after(tmp->timestamp, timestamp))
> +                                       timestamp = tmp->timestamp;
> +                       } else {
> +                               /*
> +                                * Use the current time if the fence is
> +                                * currently signaling.
> +                                */
> +                               timestamp = ktime_get();
> +                       }
> +               }
>         }
>
>         if (count == 0)
> -               return dma_fence_get_stub();
> +               return dma_fence_allocate_private_stub(timestamp);
>
>         array = kmalloc_array(count, sizeof(*array), GFP_KERNEL);
>         if (!array)
> diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
> index f177c56269bb..ad076f208760 100644
> --- a/drivers/dma-buf/dma-fence.c
> +++ b/drivers/dma-buf/dma-fence.c
> @@ -150,10 +150,11 @@ EXPORT_SYMBOL(dma_fence_get_stub);
>
>  /**
>   * dma_fence_allocate_private_stub - return a private, signaled fence
> + * @timestamp: timestamp when the fence was signaled
>   *
>   * Return a newly allocated and signaled stub fence.
>   */
> -struct dma_fence *dma_fence_allocate_private_stub(void)
> +struct dma_fence *dma_fence_allocate_private_stub(ktime_t timestamp)
>  {
>         struct dma_fence *fence;
>
> @@ -169,7 +170,7 @@ struct dma_fence *dma_fence_allocate_private_stub(void)
>         set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
>                 &fence->flags);
>
> -       dma_fence_signal(fence);
> +       dma_fence_signal_timestamp(fence, timestamp);
>
>         return fence;
>  }
> diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
> index 0c2be8360525..04589a35eb09 100644
> --- a/drivers/gpu/drm/drm_syncobj.c
> +++ b/drivers/gpu/drm/drm_syncobj.c
> @@ -353,7 +353,7 @@ EXPORT_SYMBOL(drm_syncobj_replace_fence);
>   */
>  static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
>  {
> -       struct dma_fence *fence = dma_fence_allocate_private_stub();
> +       struct dma_fence *fence = dma_fence_allocate_private_stub(ktime_get());
>
>         if (IS_ERR(fence))
>                 return PTR_ERR(fence);
> diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
> index d54b595a0fe0..0d678e9a7b24 100644
> --- a/include/linux/dma-fence.h
> +++ b/include/linux/dma-fence.h
> @@ -606,7 +606,7 @@ static inline signed long dma_fence_wait(struct dma_fence *fence, bool intr)
>  void dma_fence_set_deadline(struct dma_fence *fence, ktime_t deadline);
>
>  struct dma_fence *dma_fence_get_stub(void);
> -struct dma_fence *dma_fence_allocate_private_stub(void);
> +struct dma_fence *dma_fence_allocate_private_stub(ktime_t timestamp);
>  u64 dma_fence_context_alloc(unsigned num);
>
>  extern const struct dma_fence_ops dma_fence_array_ops;
> --
> 2.34.1
>